Reciprocating electric motor



Oct. 23 1923."

- G.- MAZZA RECIPROCATING ELECTRIC MOTOR Filed Apr-11 1129. 1921 Patented Deals, 1923.

UNITED STATES some man er roam, ITALY.

RECIPBOCA'IHG ELECTRIC IO'I'OB,

Application lled April 1'8,

To all whom itmuzy concern:

Be it known that I, GUIoo MAZZA, a subject of the King of Italy. and resident of 24 via Ospedale, Turin, in the Kingdom of Italy, have invented certain new and useful Improvements in. Reciprocating Electric Motors; and I do hereby declare the follow ing to be a full,'clear, and exact description of the invention, such as will enable others skilled in the art to which-it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

This invention relates to reciprocating electric motors, more particularly for percussive tools, of the kind comprising an electro-magnet whose core is nioved in one direction yelectro-xnagne tically and in the go other direction by spring' 'means.

' The present invention consists of a reciprocating electric motor of thekind stated, characterized in that the casin of magnetic material for the coil of the e ectro-magnet al is constituted by substantially C-shaped plates or strips spaced around the coil and en radial grooves provided in the outer surfaces of insulated'end covers. This arrangement eliminates eddy or Foucalt cur- 30 rents which tend to heat up the motor and,

' owin to the large surface of the coil exto the air, providesfor efiecting coolingrof the inner .parts. I

he invention also consists of the novel 35 construction and. arrangement of parts 1n a tool equipped with my improved electric motor, including an automatic switch comprisin movable contact blocks which are broug t into and out of contact, during the reciprocating of the core of the electro-mag:

net, in such. manner as to reduce sparking and to avoid all possibility of shocks to the operator. I l

A form of the invention as applied to a percussive tool orhammer is illustrated, by way of example on the accompanying draw ing wherein I ig. 1 is a longitudinal section of a mechanicalhammer embodying my invention. Fig. 2 is a crom section of sameon hne A,B,Fig.1.

Fig. 3 is a diagrammatic sectioned viewof the switch. V

Fig. 4 is a detailed view-of, the switclL-i- 1921. Serial Io. 460,677.

The mechanical hammer is substantially constructed of a coil 14, arranged in a cage formed by end covers 16 of insulating material .and C shaped plates 17 of magnetic material spaced equally around the coil and mounted in radial rooves provided in the outer surfaces, of t e insulated covers. A

'sleeve or liner 13 of suitable material is secured inside the coil and is closed at one fool carrier connected with the casing The sleeve 19 projects insidethe coil fora suitable distance and the tool carrier 18 constructed of .a cylindricalrod of magnetic material is fitted in the sleeve and projects outside this latter for a distance slightly exceeding the working motion. Said projecting portion carries a block of nonmagnetic and very hard material 51. The core 23 is movable longitudinally inside the coil 14 and is formed by a bundle of'sheets of magnetic material riveted to each other. Thesheet inner ends constituting the core are suitably soldered to each other in order to form a sin 10 block and the outer enlarged core en carries a conical axial recess 25 and an outer flange 26. A helical spring 27 resting on the upper horizontal ends of plates 17 and the flange 26 tend to force thecore outside the coil. The casing 15 provided at its upper part with a handle is divided by means of partitions 36'and 37 into three compartments communicating with each other through openings of the partitions. The lower chamber contains'the coil 14; the central 'one the core :head 38 and in the upper chamber is secured the automatic switch and an ordinary switch 0 rated by hand by means of a stud 46. he 'switchis constructed of sectors ofconductive material 39 and 40 secured to the insulating disc 41. One of the outer conductors 42gc6nnects' to one ofsaidsectors, whilethe;

other sector is electrically to oneof the opposite leaf springs 32 secured to the plug 43 of insulating materlal. The other leaf spring is electrically connected with the coil 14, to which connects the other outer conductor 42. Each of the axially'dlsposed leaves 32 is provided at its free end w th an outer insulatin block 33 and at an intermediate point with a conductin block 34 secured to the leaf spring inner ace. The blocks 33 are so arranged in the core recess that, when the core has reached the end of its motion outside the coil, they rest on the conical surface of the recess thus br1ng ing the leaf springs 32 nearer and establishing the contact between the blocks 34. The

distance between the leaf springs is regulated by means of a wedge 53 secured at the end of a set screw 44, so that by winding or unwinding said screw, it is possible to place said leaf springs at the distance required for a regular working. The ordinary switch is constituted by a conducting sector arranged '-laterally of the sectors 39, 40 n such a way as to come into contact with said sectors and move away from them by means of a rod 46 suitably mounted on the handle 35.

The contact blocks 34 of the automatic switch are rotected by a plate of suitable material and the core is provided with small openings through which the lower part of the recess communicates with the gap between the core and sleeve 13 allowing the lubricating oil to enter the recess and lubricate the blocks 33.

To operate the tool the conductors 42 are c'onnected toa suitable source of electrical energy; then whilst grasping the handle of r the tool, the operator depresses the rod 46 thereby closing the switch sectors 39, 40 by means of the bridge piece or sector 45 (Fig. 3), and completing the circuit forthe current through the coil 14 of the electromagnet whose core 23 is normally constrained by the spring 27 to a position where the contact 34, 34 included in the circuit are closed. Immediately the coil is ener ized the core is drawn, against the action 0 the spring, towards the tool carrier or holder 18 so that it contacts with the anvil-piece 51 and im parts a blow to the tool carried by the tool holder. At the end of the travel of the core in this direction the spring actuated contact 34, 34, move apart (permitted by the slight taper of the opening 25 in the core head) thus interrupting the circuit and deenergizing the coil whereupon the spring 27 acts to withdraw the core to its original position when the contacts are again closed and the hereinbefore described operation is repeated so long as the operator presses down the switch rod 46.

Claims:

*1. In a reciprocating electric motor, a

magnet coil, a casing for .the latter comprising a plate of insulating material at each end of the coil, and connecting members .of

magnetic material spaced around the coil and having end portions mounted in radial grooves formed in the end plates.

2. In a reciprocating motor, a magnet coil casing comprising two cover plates of in sulatlng material having radial grooves formed therein, and connecting strips of magnetic material having angular end portions mounted in the grooves.

3. In a reciprocating motor, a magnetic coil, a core arranged to reciprocate therein and having a conical recess, an automatic switch comprising spring arms extending into the recess and contacts on said arms movable into and out of contact by the reciprocations of the core.

4. In a reciprocating motor, a magnetic coil, a core arranged to reciprocate therein and having an axially arranged conical re-. cess formed in one end, an automatic switch comprising spring arms extending into the recess, insulating members interposed between the ends of the arms and the wall of the recess, and contacts on said arms movable into and out of contact by the reciprocations of the core. Y

5. In-a reciprocating motor, a magnetic coil, a core arranged to reciprocate therein and having an axially arranged conical recess formed in one end, an automatic switch comprising spring arms extending into the recess, insulating members on the free ends of said arms normally engaging the wall of the recess, and switch contacts on said arms normally held in engagement by the arms. V

6. In a reciprocating motor, a magnetic coil, a core arranged to reciprocate therein and having a conical recess formed in one end, an automatic switch comprising two contacts, spring arms carrying the latter and extending into the conical recess, said arms being operable bythe wall of the recess to move the contacts into engagement means including the contacts to energize the coil to withdraw the core from the arms, and means to return the core into contact with the arms.

7. In a reciprocating motor, a magnetic coil, a core arranged to reciprocate therein and having a conical recess formed in one end, an automatic switch comprising two contacts, spring arms carrying the latter and extending into the conical recess, a spring, for moving the core towards the arms to close the contacts, and means including. the contacts to energize the coil whereby the core is moved against the action of the spring.

8. In a reciprocating motor, a ma etic coil, a core arranged to reciprocate t erein and having a conical rem in one end, an automatic switch-comprising two contacts,

spring arms carrying the latter and havingtheir free ends extending into the recess, insulating members interposed between the free ends of the arms and the wall of the recess, a spring normally holding said wall in engagement with the insulating members" to close said contacts, and means including the contacts to energize the coil to move the core against the'actlon of the spring to open the contacts. J

9. In a reciprocating motor, a magnetic coil, a core arranged to reciprocate therein, and, having a conical recess in one end, an

automatic switch comprising two electrical contacts, spring arms carrying the latter projecting into the recess and operable by the movements of the core to make and breakthe contacts, and a protecting plate my'invention, I have si substantially surrounding the contacts, for

the purpose specified.

10. In a reciprocating motor, a magnetic coil, a core arranged to reciprocate therein and having a conical recess in one end, two

electrical contacts, spring arms carrying the latter projecting into the recess and operable by the movements of the core to make and break the contacts, a pair of switch plates, means electrically connecting one of the plates with one of the spring arms, means electrically connecting the other plate with the coil, and a hand operated bridge-plate for electrically connecting the plates to complete the'circuit.

In testimony that I claim the foregoing as ed 111 name. UID MAZZA. 

